Full-length murine fibroblast growth factor (FGF) receptor 1 (FGFR-1L) cDNA was introduced into the FDC-P1 mouse myeloid progenitor cell line, which lacks FGF receptors and depends on interleukin 3 (IL-3) or granulocyte/macrophage colony-stimulating factor (GM-CSF) for its proliferation and survival. The expression of the FGFR-1L gene in FDC-P1 cells allowed these cells to grow in the presence of FGF and heparin. The resulting cell line, designated FD FGFR-1L.A, exhibited a more mature myeloid phenotype than did the parental FD FGFR-1L cells or uninfected FDC-P1 cells. They formed mainly dispersed colonies in soft-agar cultures when grown in the presence of FGF and heparin, suggestive of myeloid differentiation. The cells can be switched between growth on FGF/heparin and IL-3. Northern blot analysis and cytochemical staining demonstrated that FD FGFR-1L.A cells expressed myeloperoxidase mRNA and protein, biochemical markers specifically expressed during differentiation from the promyelocytic to the granulocytic stages, whereas the parental FD FGFR-1L cells and FDC-P1 cells failed to express this marker. These results indicate that the expression of FGFR-1L by FDC-P1 cells transmitted signals for growth in the presence of FGF and heparin and generated an additional signal for early myeloid differentiation but failed to commit FD FGFR-1L.A cells to terminal differentiation. This in vitro culture system can be used for molecular analysis of the regulation of cellular growth and differentiation mediated by the FGFs and their receptors.